65 lines
3.9 KiB
HTML
65 lines
3.9 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Just-In-Time compiler" />
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<meta name="abstract" content="A Just-In-Time (JIT) compiler is a platform-specific compiler that generates machine instructions for each method as needed." />
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<meta name="description" content="A Just-In-Time (JIT) compiler is a platform-specific compiler that generates machine instructions for each method as needed." />
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<meta name="DC.Relation" scheme="URI" content="runtperf.htm" />
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<meta name="DC.Relation" scheme="URI" content="jitde.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2006" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Just-In-Time compiler</title>
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</head>
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<body id="jit"><a name="jit"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Just-In-Time compiler</h1>
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<div><p>A Just-In-Time (JIT) compiler is a platform-specific compiler that
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generates machine instructions for each method as needed.</p>
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<p>For more information about using the JIT compiler, and about the difference
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between the JIT compiler and direct processing, see the following pages:</p>
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<blockquote> <p><a href="runtperf.htm">Java™ runtime performance considerations</a>.</p>
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<p><a href="jitde.htm">Comparison of the JIT compiler and direct processing</a>.</p>
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</blockquote>
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<div class="note"><span class="notetitle">Note:</span> The default setting for <span class="keyword">i5/OS™</span> is
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to interpret (not compile) Java methods by using the Mixed-Mode Interpreter
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(MMI). MMI profiles each Java method as it interprets it. After reaching
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the threshold specified by the os400.jit.mmi.threshold property, MMI then
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specifies that <span class="keyword">i5/OS</span> use
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the JIT compiler to compile the method.</div>
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<p>For more information, see the entries for the java.compiler property and
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the os400.jit.mmi.threshold property in the appropriate list of Java system
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properties:</p>
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<blockquote> <p><a href="sysprop2.htm">Java system properties for Java 2
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SDK (J2SDK), Standard Edition</a></p>
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</blockquote>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="jitde.htm">Comparison of Just-In-Time compiler and direct processing</a></strong><br />
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If you are trying to decide whether to use the Just-In-Time compiler
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or direct processing mode to run your Java program, this table provides additional
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information to help you make the best choice for your situation.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="runtperf.htm" title="Understanding the following considerations can help you improve the performance of your Java applications.">Java performance considerations</a></div>
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</div>
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</div>
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</body>
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